Diagnosis of autoimmune skin disease in the dog: correlation between histopathologic, direct immunofluorescent and clinical findings

Trunk-dominant and classic facial pemphigus foliaceus in dogs - comparison of anti-desmocollin-1 and anti-desmoglein-1 autoantibodies and clinical presentations

BACKGROUND

Canine trunk-dominant pemphigus foliaceus (PF) is mentioned rarely in the literature.

HYPOTHESIS/OBJECTIVES

The goal of this study was to provide clinical description of trunk-dominant PF and to demonstrate the prevalence of serum antikeratinocyte, anti-desmocollin-1 (DSC1) and anti-desmoglein-1 (DSG1) antibodies, and determine their diagnostic value in this particular PF phenotype.

MATERIALS AND METHODS

Clinically relevant information was collected from 31, 25 and 34 dogs with trunk-dominant and facial PF and superficial pyoderma (SP), respectively. Sera from these dogs were tested for antikeratinocyte, anti-DSC1 and anti-DSG1 antibodies using indirect immunofluorescence on canine tissues and DSC1- and DSG1-transfected cells. Sera from healthy dogs and dogs with clinically irrelevant diseases served as controls.

RESULTS

Footpad involvement and grouped/polycyclic lesion organisation were identified as features of both PF phenotypes, and not of SP. Antikeratinocyte immunoglobulin (Ig)G was not specific for canine PF. By contrast, antigen-specific IgG was detected only in PF sera; anti-DSC1 IgG in 100% and 58% of dogs with facial and trunk-dominant PF, respectively, and anti-DSG1 IgG in 7% of dogs with trunk-dominant PF only.

CONCLUSIONS

Trunk-dominant PF shares DSC1 as a major autoantigen with facial PF. The ability to detect anti-DSC1 IgG is lower in trunk-dominant PF, yet despite the lower sensitivity, the positive predictive value and accuracy of this particular anti-DSC1 IgG test are high. A negative test result, however, cannot exclude the diagnosis, and characteristic clinical features such as footpad involvement and/or grouped/polycyclic lesions must be considered when distinguishing trunk-dominant PF from its most relevant differential diagnosis: SP.

Pemphigus foliaceus in two pet Nigerian Dwarf goats

Two male Nigerian Dwarf pet goats from a group of three living in rural southern Wisconsin, USA, presented at the same time with an eight-month history of pruritus and marked crusting on head, axillae and inguinal regions. Parasite investigations were negative, and there was no response to antiparasitic treatment. Fungal and bacterial cultures did not reveal a cause. Histopathology was consistent with a diagnosis of pemphigus foliaceus, and goats were treated with immunosuppressive doses of injectable dexamethasone sodium phosphate. After six weeks of treatment, clinical remission was achieved, and immunosuppressive therapy was continued. Three months later, goat 2 developed presumptive viral pneumonia; necropsy reported presumptive caprine arthritis encephalitis virus. One year into treatment, goat 1 developed similar clinical signs and was euthanased. In goats, pemphigus foliaceus is rare and can be treated using glucocorticoids, but as in other species, chronic immunosuppression increases susceptibility to infections.

Successful treatment of pemphigus foliaceus in a Berrichon du Cher ram with methylprednisolone acetate

BACKGROUND

Pemphigus foliaceus is a severe, autoimmune blistering skin disease, which is described in humans and some animal species. In small ruminants pemphigus foliaceus has rarely been described and, to the best of the authors' knowledge, little information is available about successful treatment in sheep.

AIM

This case report describes a Berrichon du Cher ram with the presumed diagnosis of pemphigus foliaceus.

METHODS

The ram was treated with methylprednisolone acetate 40 mg at a dosage of 2.5 mg/kg in one subcuticular injection at four week intervals over a one year period, with regular observation of clinical parameters. Four months after treatment was initiated the haematological parameters showed lymphopenia and leukopenia; some enzyme activities were substantially increased.

RESULTS

The ram's dermatological condition improved to the point of complete healing of the affected skin. The ram was discharged in good condition. No adverse effects, except an elevation of some enzymes associated with liver function, were observed. At postmortem examination moderate fatty liver syndrome was the only abnormality found.

CONCLUSIONS AND CLINICAL IMPORTANCE

This case report demonstrated that long term therapy with methylprednisolone acetate in a sheep with pemphigus foliaceus did not have a negative effect on clinical parameters. Nevertheless, due to the extended statutory withdrawal period resulting from the regular administration of glucocorticoids, such a therapeutic option must be critically assessed in food producing animals.

Canine pemphigus foliaceus with concurrent immune-mediated thrombocytopenia

A 3 yr old wirehaired fox terrier was presented to his primary care veterinarian with fever, thrombocytopenia, and generalized crusting dermatitis. The skin lesion had progressed for at least 18 days, and thrombocytopenia had developed 3 days before presentation. Histopathology and direct immunofluorescence studies of the skin were consistent with pemphigus foliaceus (PF). Immunofluorescence revealed immunoglobulin G deposition around the keratinocytes in the stratum spinosum. A diagnosis of immune-mediated thrombocytopenia (IMT) was confirmed by the presence of platelet surface-associated immunoglobulin using flow cytometry. Systemic immunosuppressive therapy with cyclosporine and azathioprine was effective, and the dog survived for >2 years from the initial presentation. IMT is rarely associated with PF. This appears to be the first detailed report of a definitive diagnosis of concurrent PF and IMT in a dog. The authors' findings indicate that canine PF could be complicated by hematologic immune-mediated diseases such as IMT.

Successful treatment of a novel generalized variant of canine discoid lupus erythematosus with oral hydroxychloroquine

Discoid lupus erythematosus (DLE) is a common canine autoimmune disease that usually manifests as a localized ulcerative and scarring nasal dermatitis. We report herein a generalized variant of canine DLE successfully treated with the antimalarial immunomodulator hydroxychloroquine (HCQ). A 9-year-old hairless Chinese crested dog was presented with annular and polycyclic hyperpigmented and scaly skin lesions with central erosions, hypopigmentation and/or scarring on the trunk, neck and lateral extremities. Associated systemic signs were not seen. The clinical diagnosis of generalized DLE was supported by the demonstration of lymphocyte-rich interface dermatitis with epidermal atrophy and dermo-epidermal deposition of immunoglobulins and activated complement. As for human DLE, treatment was initiated with HCQ at 5 mg/kg once daily along with 2 weeks of 0.1% tacrolimus ointment and restriction of sun exposure. Over the following year, complete remission was maintained with HCQ at 5 mg/kg orally once daily with the exception of three relapses; two occurred during treatment induction and the third arose when the frequency of HCQ administration was reduced to every other day. Disease flares were controlled with 0.1% tacrolimus ointment alternating with 0.1% prednicarbate cream once daily for 5-10 days. Altogether, adverse drug events were not seen with this regimen. In summary, clinically, histologically and immunologically, this dog's disease mirrored the generalized discoid variant of chronic cutaneous lupus erythematosus of humans. The apparent benefit of HCQ, its safety and low cost warrant future investigations of its use for treatment of canine cutaneous lupus variants.

Immunomapping of desmosomal and nondesmosomal adhesion molecules in healthy canine footpad, haired skin and buccal mucosal epithelia: comparison with canine pemphigus foliaceus serum immunoglobulin G staining patterns

Pemphigus foliaceus (PF) is the most common canine autoimmune skin disease. In contrast to human PF (hPF), desmoglein-1 is a minor autoantigen in the canine disease. The major autoantigen(s) of canine PF (cPF) remain(s) unknown, which limits the ability to perform mechanistic studies of lesion formation and the development of novel diagnostic and therapeutic strategies for this disease. The immunofluorescence patterns of selected desmosomal (desmoglein-1, desmoglein-3, desmocollin-1, desmocollin-3, desmoplakin-1/2, plakoglobin and plakophilin-1) and nondesmosomal adhesion proteins (E-cadherin, claudin-1, zona occludens-1 and occludin) in healthy canine footpad, haired skin and buccal mucosal epithelia were determined using hPF and pemphigus vulgaris sera and specific antibodies. The immunostaining patterns were then compared with that of indirect immunofluorescence staining with 66 cPF sera. Most cPF sera (58 of 66; 88%) exhibited positive staining along keratinocyte margins in the stratum spinosum and stratum granulosum of canine footpad. One serum contained autoantibodies binding solely to stratum granulosum keratinocytes. Concurrent intercellular fluorescence in the stratum basale was limited to seven of 66 cPF sera (11%). Only 12 of 66 cPF sera (18%) also exhibited positive IF staining of the buccal mucosa. This study confirms the immunological heterogeneity of cPF immunoglobulin G autoantibodies. Moreover, the major indirect immunofluorescence staining pattern and the inability of most cPF sera to label the buccal mucosa closely matched that of desmocollin-1. These observations warrant further investigation of desmocollin-1 as a potential major cPF autoantigen.

Pemphigus foliaceus-like drug reaction in a 3-month-old crossbreed dog treated for juvenile cellulitis

Two weeks after administration of routine vaccinations, a 3-month-old, male crossbreed dog developed cutaneous lesions that were clinically and histopathologically consistent with a diagnosis of juvenile cellulitis. The patient was treated with systemic antibacterial, antibacterial ophthalmic ointment and nonsteroidal anti-inflammatory drugs. Within 1 week, new skin lesions that were clinically, histopathologically and immunohistochemically consistent with pemphigus foliaceus developed. The latter completely resolved following drug withdrawal, suggesting a pemphigus foliaceus-like drug reaction. However, the initial lesions persisted and required glucocorticoid therapy to effect resolution. To the authors' knowledge, this is the first reported case of a puppy developing juvenile cellulitis followed by a pemphigus foliaceus-like reaction shortly thereafter, in response to drug therapy.

Unusual dermatological toxicity of hydroxyurea in two dogs with spontaneously occurring tumours

Hydroxyurea is a chemotherapeutic agent used to treat hypereosinophilic syndrome, mast cell tumours and many myeloproliferative disorders. It is usually well tolerated; however, reported side effects include myelosuppression and gastrointestinal complications as well as cutaneous toxicity, in very rare cases. We report the unusual appearance of onychomadesis involving several claws on all feet in two canine patients receiving long-term hydroxyurea treatment. The healing of nail lesions required cessation of treatment in one dog and dose reduction in the second animal, supporting a strict relationship between onychopathy and administration of hydroxyurea. The aim of this case report is to increase clinical awareness of dermatological toxicity associated with long-term administration of hydroxyurea.

A review of autoimmune skin diseases in domestic animals: I - superficial pemphigus

In humans, the pemphigus denomination encompasses a group of autoimmune blistering skin diseases with intraepidermal separation resulting from cell-cell detachment by acantholysis. Entities are classified based on the level of blistering in the epidermis, and both superficial (pemphigus foliaceus, IgA pemphigus) and deep (pemphigus vulgaris, pemphigus vegetans and paraneoplastic pemphigus) variants are recognized. In domestic animals, subsets of pemphigus have been recognized since the mid-1970s, and the disease classification resembles that used for human patients. This article reviews up-to-date knowledge on the epidemiology, clinical signs, histopathology, immunopathology and treatment outcome of superficial pemphigus in domestic animals. Detailed information on canine, feline, equine and caprine pemphigus foliaceus, canine and feline pemphigus erythematosus and canine panepidermal pustular pemphigus is provided.

Pemphigus Foliaceus in 91 Dogs

A retrospective study of 91 dogs with pemphigus foliaceus was performed. Clinical signs of the disease included crusts (n=79), pustules (n=36), and alopecia (n=33). Lesions were most common on the trunk (n=53), inner pinnae (n=46), face (n=37), and foot pads (n=32). Cytological evaluation revealed acantholytic keratinocytes in 37 of 48 dogs. Results of combination treatment with prednisolone and azathioprine were comparable to results with prednisolone therapy alone. More than half of the dogs achieved remission with appropriate therapy, and another 25% significantly improved.

Clinical, immunological and histopathological findings in a subpopulation of dogs with pododermatitis

Clinical, immunological and histopathological findings in 20 adult dogs of varying breeds with chronic (>or=6 months) inflammation confined to the pedal skin were compared over a 2-year period with those of a group of age-matched controls (n=20). All affected dogs were pruritic but systemically well. Lesions were present on all four feet in 18/20 cases. Affected feet were characteristically erythematous, swollen, painful and alopecic. Sinus tracts were evident in 4/20 dogs. Despite a methodical series of diagnostic tests, no underlying cause was identified. None of the dogs responded to antimicrobial therapy administered for 8 weeks, none had evidence of ectoparasitism and none satisfied the criteria for atopic dermatitis. There was no response to a dietary trial using a novel protein source. The condition was characterized histopathologically by epidermal hyperplasia, hyperkeratosis, spongiosis, dermal oedema and perivascular aggregates of lymphocytes and plasma cells. Clinical signs did not correlate with histopathological findings. Affected dogs had significantly elevated serum IgG and IgM concentrations. The results of lymphocyte proliferation assays and phenotypic studies to determine the relative percentage of CD3+, CD4+, CD8+ and CD21+ lymphocyte subsets, and the ratio of CD4+/CD8+ cells were not significantly different between groups. No age, sex or seasonal predilections were noted. All dogs subsequently responded to immunosuppressive doses of prednisolone or cyclosporin. The term immunomodulatory-responsive lymphocytic-plasmacytic pododermatitis is proposed to denote what may be a previously unrecognized condition in some dogs with pododermatitis of undetermined aetiology.

Desmoglein-1 is a minor autoantigen in dogs with pemphigus foliaceus

The majority of human patients with pemphigus foliaceus (PF) have circulating IgG autoantibodies that target conformational epitopes on the desmosomal cadherin desmoglein-1 (dsg1). Limited studies using immunoblot techniques suggested that the principal autoantigen in dogs with PF might also be dsg1. It was the objective of this study to test this hypothesis. A comprehensive survey of canine PF sera was conducted using a novel screening strategy that detects conformational epitopes. This method consists of the ectopic expression of canine dsg1 at the surface of human 293T epithelial kidney cells and their live screening, i.e. prior to fixation. Out of seven control human PF sera that bound to canine epidermis, three (57%) contained IgG autoantibodies that recognized ectopically expressed canine dsg1 with a membrane and punctate pattern. Out of 83 canine PF sera only five (6%) contained IgG that recognized canine dsg1. Consistent with findings for human PF sera obtained in this study, autoantibody binding was conformation- and glycosylation-dependent as demonstrated by calcium chelation with EDTA and tunicamycin or wheat germ agglutinin treatment, respectively. In conclusion, these studies establish canine dsg1 as a minor autoantigen for canine PF. Antigenic epitopes appear to be conformation- and glycosylation-dependent.

Detection of circulating autoantibodies using living keratinocyte staining on MCA-B1 method in dogs with pemphigus foliaceus

In this study, we compared the sensitivity and specificity of three immunofluorescence techniques used to detect circulating autoantibodies in dogs with pemphigus foliaceus (PF); living keratinocyte staining on a canine keratinocyte cell line, MCA-B1, indirect immunofluorescence (IIF) on canine lip and IIF on bovine esophagus. Sera from canine PF cases were positive in four out of 27 dogs (14.8%) using living keratinocyte staining on MCA-B1 cells method, and five (18.5%) and eight sera (29.6%) using IIF on canine lip and bovine esophagus methods, respectively. By contrast, none of the 31 sera from dogs with non-pemphigus dermatoses reacted with MCA-B1 cells, whereas two (6.5%) as well as five sera (16.1%) obtained from those dogs showed positive reactivity with IIF on canine lip and bovine esophagus, respectively. Our results suggest that, although it exhibits the least sensitivity, the positive reactivity obtained by living keratinocyte staining on MCA-B1 cells can support the diagnosis of canine PF.

Prolonged remission after immunosuppressive therapy in six dogs with pemphigus foliaceus

Limited information is available on the long-term outcome of treatment of pemphigus foliaceus in dogs. The purpose of this study is to report that a prolonged remission can occur after discontinuation of immunosuppressive regimens in some animals with this disease. Six dogs were diagnosed with pemphigus foliaceus based on suggestive clinical signs and histopathology. These patients were treated either with immunosuppressive doses of oral glucocorticoids or with a combination of oral glucocorticoids and azathioprine. After clinical signs underwent complete remission, which occurred 1.5-5 months after immunosuppression was initiated, the drugs were tapered progressively and eventually withdrawn. The total duration of immunosuppressive therapy varied between 3 and 22 months. Skin lesions of pemphigus foliaceus did not recur for 1.5-6 years after treatment was stopped. These observations suggest that, in some dogs with pemphigus foliaceus, immunosuppression can lead to long-term remission of skin lesions, and that discontinuation of treatment is not necessarily followed by a recurrence of clinical signs.

Outcome and complications associated with treatment of pemphigus foliaceus in dogs: 43 cases (1994-2000)

OBJECTIVE

To identify factors affecting prognosis, outcome, and complications associated with pemphigus foliaceus in dogs.

DESIGN

Retrospective study.

ANIMALS

43 dogs with pemphigus foliaceus.

PROCEDURE

Medical records were reviewed for signalment, age at diagnosis, duration to diagnosis, body area affected, initial immunosuppressive regimens and concurrent use of antimicrobials and sucralfate or histamine receptor 2 blocking agent, adverse effects of treatment, duration of treatment, number of visits for follow-up care, cause of death, and credentials of the veterinarians responsible for continued care.

RESULTS

The case fatality rate was 60.5%. Factors significantly correlated with survival time included concurrent use of antimicrobials during initiation of immunosuppressive treatment and a lower number of adverse effects to treatment. Treatment times lasting more than 10 months from diagnosis correlated significantly with survival.

CONCLUSIONS AND CLINICAL RELEVANCE

Treatment with or prophylactic use of antimicrobials may be warranted during initial immunosuppressive treatment. The inverse correlation between survival time and number of adverse treatment effects was not unexpected because it was reflective of the owners' decision to euthanatize their dogs and of corticosteroid-related secondary diseases. Survival beyond the tenth month of treatment predicted long-term survival, which suggests that dogs require careful management during the early months of treatment.

Production of recombinant extracellular domains of canine desmoglein 1 (Dsg1) by baculovirus expression

The aim of this study was to generate a recombinant protein to represent the entire extracellular domain of canine desmoglein 1 (Dsg1), a desmosomal cell-cell adhesion molecule, by the baculovirus expression system. Cotransfection of a baculovirus transfer vector containing the cDNA for the entire extracellular domain of canine Dsg1 with baculovirus DNA into insect cells resulted in the secretion of soluble canine Dsg1 into insect culture supernatants. Immunoreactivity of 11 human pemphigus foliaceus (PF) sera against the cell surface of canine keratinocytes was completely removed when the sera were preincubated with the canine Dsg1 baculoprotein. This recombinant canine Dsg1 produced by baculovirus shares the major epitopes of the authentic canine Dsg1 recognized by human PF sera, and will be useful in studying the molecular pathophysiological mechanisms in PF and impetigo in canine patients.

Desmoglein-3 is a target autoantigen in spontaneous canine pemphigus vulgaris

Pemphigus vulgaris (PV) is an autoimmune blistering skin disease of humans and companion animals. In human patients, PV is associated with the production of IgG autoantibodies specific for keratinocyte desmosomal glycoproteins of the cadherin family. The purpose of this study was to determine whether antikeratinocyte IgG autoantibodies were present in the skin and serum of dogs with PV, and also to identify the canine PV autoantigen(s) targeted by circulating autoantibodies. Eleven dogs were selected because of the microscopic demonstration of suprabasal epithelial acantholysis. Direct immunofluorescence revealed the presence of IgG autoantibodies bound to the membrane of keratinocytes in skin biopsy specimens of 8/9 dogs (89%). Using indirect immunofluorescence, serum-circulating IgG autoantibodies were found in 10/11 (91%) and 5/11 (45%) dogs, using normal canine gingiva and cultured canine oral keratinocytes, respectively. By immunoblotting using cultured canine oral keratinocyte protein lysates, IgG autoantibodies from 7/9 (78%) tested dogs recognized a 130-kDa antigen that comigrated with that identified by rabbit polyclonal antibodies raised against desmoglein-3. This 130 kDa antigen was confirmed to represent the canine equivalent of human desmoglein-3 by immunoprecipitation-immunoblotting. The results of these studies provide evidence that the canine desmoglein-3 homologue is a major autoantigen in dogs with PV. These observations further establish spontaneous canine PV as a natural model for research on pathogenesis, etiology and novel therapeutic approaches for this disease of humans.

Comparison of three monoclonal and three polyclonal antibodies in the immunohistochemical diagnosis of canine autoimmune skin diseases

The aim of this study was to evaluate the utility of three monoclonal antibodies (mAbs), and two anticanine IgG and one anticanine IgM polyclonal antibodies (pAbs) for the immunohistochemical diagnosis of canine autoimmune skin diseases. Skin biopsies from 11 cases of pemphigus (7 foliaceus, 3 vulgaris and 1 erythematosus), 12 cases of discoid lupus erythematosus (DLE) and 12 cases of chronic hyperplasic dermatitis were used. The CA4E7 mAb (IgG1 + IgG2) showed similar sensitivity, but higher specificity and lower background than the two anti-IgG pAbs for the immunohistochemical diagnosis of pemphigus and DLE. The CA4F1 mAb (IgG2) and CA3H1 mAb (IgG2) showed moderate and low interepithelial reactivity, respectively, in autoimmune skin diseases, but strong staining of the cytoplasm of plasma cells of the inflammatory infiltrates. These results suggest that the CA4E7 mAb may be valuable in the immunohistochemical diagnosis of such disorders.

Novel feline autoimmune blistering disease resembling bullous pemphigoid in humans: IgG autoantibodies target the NC16A ectodomain of type XVII collagen (BP180/BPAG2)

In humans and dogs, bullous pemphigoid (BP) is an autoimmune blistering disease associated with the production of basement membrane autoantibodies that target the 180-kd type XVII collagen (BP180, BPAG2) and/or the 230-kd plakin epidermal isoform BPAG1e (BP230). In two adult cats, an acquired dermatosis and stomatitis was diagnosed as BP subsequent to the fulfillment of the following criteria: 1) presence of cutaneous vesicles, erosions, and ulcers; 2) histologic demonstration of subepidermal vesiculation with inflammatory cells, including eosinophils; 3) in vivo deposition of IgG autoantibodies at the epidermal basement membrane zone; and 4) serum IgG autoantibodies targeting a 180-kd epidermal protein identified as type XVII collagen. In both cats, the antigenic epitopes targeted by IgG autoantibodies were shown to be situated in the NC16A ectodomain of type XVII collagen, a situation similar to that of humans and dogs with BP. Feline BP therefore can be considered a clinical, histopathologic, and immunologic homologue of BP in humans and dogs.

Immunopathogenesis of canine aural haematoma

Data are presented from 15 dogs with aural haematoma. The series included six Labrador retrievers and four golden retrievers and the mean age was 8.0 +/- 3.02 years. Five dogs had evidence of pruritic skin disease and five further cases had other concurrent disease. Haematology and serum biochemistry were normal in 12 and 13 of the 15 dogs, respectively. All dogs were Coombs' negative and serum antinuclear antibody had negative or low titres in all the 11 cases tested. Histopathological examination of biopsies from the affected ears revealed variable degrees of erosion of auricular cartilage with fibrovascular granulation tissue filling the cartilage defects. There was minimal perichondral inflammation. The biopsies were studied by immunohistochemistry for deposition of immunoglobulin G (IgG), immunoglobulin M (IgM) and complement C3. In one dog there was basement membrane zone deposition of IgG and in another there was focal interepithelial deposition of both IgG and IgM. The findings of this study do not support an autoimmune pathogenesis for canine aural haematoma, but suggest that an early immunological event may underlie the observed cartilage erosion.

Comparative histopathology of pemphigus foliaceus and superficial folliculitis in the dog

A comparative histopathologic study of 50 cases of pemphigus foliaceus and 47 cases of superficial folliculitis in the dog was undertaken to identify those histopathologic features important in differentiating these diseases. All cases were diagnosed by the Surgical Pathology Service of the Laboratory of Pathology of the University of Pennsylvania, School of Veterinary Medicine, between January 1986 and March 1991. These cases were followed clinically to determine the accuracy of the initial histopathologic diagnosis. Data were analyzed by Fisher's exact test for discrete data and the Mann-Whitney U-test for continuous data. A probability of < 0.05 was considered statistically significant. The following breeds were affected with pemphigus foliaceus: Akita, Brittany Spaniel, Chow Chow, Collie, Dachshund, Doberman Pinscher, English Cocker Spaniel, English Setter, Golden Retriever, Siberian Husky, Laborador Retriever, Miniature Schnauzer, Old English Sheepdog, Scottish Terrier, Chinese Shar Pei, Spitz, Shetland Sheep Dog, Weimeraner, and West Highland White Terrier. An increased risk of developing pemphigus foliaceus was noted in the Akita (OR = 37.8), English Springer Spaniel (OR = 20.7), Chow Chow (OR = 12.3), Chinese Shar Pei (OR = 7.9), and Collie (OR = 3.9). Pemphigus foliaceus had a higher average density of acantholytic cells (226 +/- 22.9) than superficial folliculitis (11.8 +/- 4.6), and acantholytic cells were 183 times more likely to be present in pemphigus foliaceus. The presence of rafts of acantholytic cells occurred in pemphigus foliaceus (23/50) more often than superficial folliculitis (1/47). Recornification and reformation of pustules were, respectively, 13.4 and 3.6 times more likely to occur in pemphigus foliaceus.(ABSTRACT TRUNCATED AT 250 WORDS)

Immune-mediated skin disease in the dog and cat

Immune-mediated skin disease was recorded in 24 dogs and 11 cats by the Department of Pathology and Microbiology, University of Bristol, over the period 1973-1992. The clinical and histopathological features, together with the age, breed and sex, are given for each case. Skin biopsies from the 24 dogs in this series, together with tissue from 25 control dogs, were immunostained for IgG, IgM and C3 by direct immunoperoxidase methodology. The same technique, with species-specific antisera for IgG and IgM, was applied to skin biopsies from 10 affected cats. The correlation between clinical features, histopathology and immunohistochemistry is discussed.

Demonstration of immunoglobulins and complement in canine and feline autoimmune and non-autoimmune skin diseases with the direct immunofluorescence and indirect immunoperoxidase method

Skin sections from 71 dogs and 10 cats with bullous autoimmune skin diseases and various non-autoimmune dermatopathies were studied for the presence of immunoglobulins (canine IgG, IgM, IgA; feline IgG) and complement (canine C3) using the direct immunofluorescence method (DIF) and the indirect immunoperoxidase method (IIP). In cases of autoimmune skin diseases (9 dogs, 3 cats) both methods were of comparable sensitivity for the detection of epidermal deposits. In canine cases with non-autoimmune dermatopathies, epidermal immunoreactivity was found in 16.1% of cases with the DIF method, and in 29.0% of cases with the IIP method. With both methods, epidermal deposits were most frequently seen in skin sections of dogs with bacterial diseases. Furthermore, positive reactions were found in canine cases with hypersensitivity disorders, endocrine dermatosis, dermatomycosis, parasitic disease, cutaneous Leishmaniasis and in cases with non-specific dermatopathies of uncertain aetiology. In the majority of canine cases intercellular deposits of IgG were found. Immunohistological results should always be interpreted in conjunction with clinical and histomorphological findings in order to establish a diagnosis of autoimmune skin disease and to prevent misdiagnoses.

Immunoperoxidase staining for the detection of autoantibodies in canine autoimmune skin disease; comparison to immunofluorescence results

Skin sections from 22 dogs with autoimmune skin disease were stained with anti-canine IgG, IgM and IgA using an immunobridge immunoperoxidase method. Eight cases of lupus erythematosus, three cases of pemphigus vulgaris, and 11 cases of pemphigus foliaceus were included. Results of previously performed, direct immunofluorescence tests for the detection of canine immunoglobulin on skin were available on 17/22 cases. The immunoperoxidase method yielded an overall positive result in 59% (5/8 lupus erythematosus, 2/3 pemphigus vulgaris and 6/11 pemphigus foliaceus) versus an overall positive result of 47% for direct immunofluorescence (3/5 lupus erythematosus, 2/2 pemphigus vulgaris and 2/10 pemphigus foliaceus). The immunobridge immunoperoxidase method compared favorably to direct immunofluorescence testing of canine skin for autoantibody in cases of lupus erythematosis and pemphigus vulgaris, and was superior in cases of pemphigus foliaceus. This method should prove useful as an aid in the diagnosis of canine autoimmune skin disease.

Localization of immunoglobulins and complement by the peroxidase antiperoxidase method in autoimmune and non-autoimmune canine dermatopathies

Formalin-fixed, paraffin embedded skin biopsy specimens from 44 dogs with various dermatopathies were examined for the presence of immunoglobulins (IgG, IgM, IgA) and complement (C3) by the peroxidase antiperoxidase method (PAP). Final diagnoses of the skin diseases were determined by clinical findings, fungal and bacterial cultures, skin scrapings, serum endocrinologic tests, and histologic features of cutaneous biopsies. The dermatopathies included examples of pyoderma (folliculitis/furunculosis), demodecosis, sarcoptic mange, dermatophytosis, endocrine dermatopathy, and autoimmune skin disease (AISD). In the latter category, 7 cases of pemphigus foliaceus, 1 pemphigus vulgaris, 4 discoid lupus erythematosus (DLE) and 4 examples of indeterminate AISD were examined. Immunoglobulins, C3, or both, were localized in tissue sections from AISD (15/16), pyoderma (7/11), demodecosis (4/8) sarcoptic mange (3/3), and dermatomycosis (2/3). Endocrine dermatopathy biopsies were consistently negative for Ig and C3 (0/3). The pattern of localization was most often intercellular (31/44 positive biopsies) with basement membrane immunoreactivity in 4 cases of DLE, and 1 case of indeterminate AISD. There was no consistent correlation between histologic features of hematoxylin and eosin-stained biopsies and the presence of Ig and C3. Clinical outcome was similar in both Ig and C3 positive and negative cases of non-AISD dermatitis. The high percentage (95%) of positive results in AISD biopsies indicates the usefulness and sensitivity of the PAP method for the localization of Ig and C3. Because of the high percentage of Ig localization in pyoderma (73%), biopsy specimens with extensive inflammatory skin disease are not suitable for diagnosis of AISD. The PAP method is useful in the diagnosis of AISD in biopsy specimens with minimal inflammation. Caution is warranted in the interpretation of immunoreactivity independent of clinical and histologic information.

Progressive polysystemic immune-mediated disease in a dog

A dog with polyarthritis, angular joint deformities, and a high serum antinucleolar antibody titer was treated over a period of 20 months. During the clinical course, leukopenia, thrombocytopenia, Coombs' positive hemolytic anemia, and a pemphigus-type skin disorder developed, all of which responded to immunosuppressive therapy. It is not known whether the polysystemic disease in this dog represents a pleomorphic manifestation of canine systemic lupus erythematosus or multiple autoimmune disorders occurring in the same animal.